EP-A-0 274 322 describes a spraying installation for spraying a coating material onto articles to be coated, such as motor vehicle bodies. The term “coating material” is used to mean any material that is to be sprayed onto an article to be coated, e.g. a primer, a paint, or a varnish, etc. A station is used to re-supply coating material to an atomizer equipped with a reservoir and disposed on a robot mounted to move relative to motor vehicle bodies. That station includes coupling means for coupling to coating material circuits. The coupling means are formed by connector elements, each of which is mounted at the end of a respective coating material circuit. Each coating material circuit makes it possible, when selected, to feed the reservoir equipping the atomizer.
The re-supply station described by EP-A-0 274 322 also includes a docking unit defining an atomizer-receiving zone for receiving the atomizer equipped with its reservoir. After a stage of spraying on the articles to be coated, in order to re-supply the atomizer and its reservoir with coating material, the robot comes to place the atomizer in the atomizer-receiving zone. Then the reservoir is connected to the circuit of the coating material that is to be transferred to the reservoir, via corresponding coupling means of the docking unit. After the reservoir has been filled, the robot resumes moving the atomizer facing the articles to be coated.
When the coating material is to be changed, e.g. when the shade of paint is to be changed, then, prior to filling, the atomizer and its reservoir must be rinsed with a cleaning material. To that end, the re-supply station described by EP-A-0 274 322 also includes another connector element performing the function of coupling member for coupling to a cleaning material duct. The term “cleaning material” is used to mean any solvent adapted to remove the coating material from the surfaces of the reservoir and of the atomizer.
Prior art stations and methods take a relatively long time to change coating materials because the pressure in conventional circuits is generally limited to 6 bars, thereby resulting in a flow rate for filling the reservoir that is limited to 3000 cubic centimeters per minute (cm3/min). Thus, re-supply lasts about 20 seconds for a reservoir of 400 cm3, including 10 seconds for docking the atomizer and for connecting the reservoir to the docking unit. In an installation for painting motor vehicle bodies, such a re-supply station and such a re-supply method make it possible to coat no more than 50 vehicles per hour.
In addition, in order to limit settling-out of a coating material, in particular of a paint, when it stagnates in a circuit of a paint installation as described by WO-A-01 015 814, each coating material circuit must be made up of two distinct paths for causing the coating material to flow regularly. A “go” path brings the coating material from a pump to the coupling means of the station, while a “return” path brings the coating material back from the coupling means to the pump. Unfortunately, the costs of manufacturing, assembling, and maintaining such two-path circuits are relatively high.
A particular object of the invention is to remedy those drawbacks by proposing a station that makes fast re-supply possible, that is of simple construction, and that limits wastage and settling-out of the coating materials.